Herbal medicine or the use of plants as therapeutic substances is believed to be the oldest form of medicine. Today, herbal medicine is still a very important part of many different health systems around the world. More than 75% of the world’s population relies on herbal medicines as their primary form of health care. Every cultural group has its own beliefs and cultural traditions involving healing with herbs. For example, herbs are used as medicines in Traditional Chinese Medicine, Ayurvedic medicine, Tibetan medicine and First Nations healing traditions. Each of these health systems is based on different theories or ideas about health and healing. The herbs that are used, and the way they are used may differ.